DESCRIPTION: (Applicant's Abstract) This application is a new proposal for a FIRST Award to test suspected causal pathways leading toward early drug initiation, using a well-defined epidemiologic sample of low and normal birth weight children from an on-going study of the neuropsychiatric sequelae of low birth weight. Two distinct approaches will be used: 1) epidemiologic research, which extends the applicant's prior work on drug use etiology; and 2) behavioral laboratory research on individual differences in drug use. The sample for this research consists of 473 low birth weight and 350 normal birth weight children selected from the 1983 to 1985 list of newborns from an urban and a suburban hospital in southeast Michigan. Children were assessed initially when they were 6 or 7 years old with a follow-up assessment at age 11. In addition, a telephone interview was conducted with the mothers when the children were 8-10 years old. In the first component of the research plan, data from this longitudinal study will be analyzed to test suspected pathways from low birth weight and its sequelae to initiation of drug use by children, with a focus on attention deficit/hyperactivity disorder (ADHD). The relationship between individual vulnerability and social environmental factors, specifically parent monitoring and neighborhood disadvantage, will be examined. In the second component of the research plan, 120 children sample on the basis of prior ADHD and conduct disorder, will be recruited to participate in a laboratory study measuring risk-taking and impulsivity. The availability of longitudinal data from an epidemiologic sample, measured across distinct domains and from multiple informants, in addition to the use of laboratory measures, provides a unique opportunity to extend prior research on the etiology of drug use. Increased understanding of the interrelationship between individual susceptibility and the social environment in the causal pathway to drug use is necessary for the development of effective prevention strategies.